When gas-sterilizing medical products, e.g. using water vapour (steam), it is necessary to encapsulate the product in such a way that on one hand steam may enter (and thus sterilize) the product and on the other hand the product remains sterile after sterilization. Normally this is achieved using a sterilization barrier in form of a specialised moist penetratable porous sheet material forming at least part of the packaging material. For example, U.S. Pat. No. 6,808,691 discloses sheets for sealable sterilizing packages based on cellulose fibres (e.g. paper), paper sheets reinforced by synthetic fibres mixed with the cellulose fibres, as well as non-woven sheets obtained by a dry route and comprising only hot-bonded synthetic fibres. Also micro-porous polymeric foils have been developed. In case sterilization takes place using radiation WO 02/070024 discloses a method in which a bioactive material is enclosed in a package, the package being formed from a non-porous material allowing sterilizing radiation to penetrate yet prevents an enclosed hydrogen gas scavenger to escape.
If the entire product is to be gas sterilized the product can be placed in a pouch or bag being fully or partly penetratable to the sterilizing gas, however, if only the interior of a given product is to be sterilized and the product comprises one or more openings, then these openings can be sealed by attaching planar sheets of sterilization barrier material by e.g. welding or gluing, this allowing the interior of the product to be sterilized through the one or more openings.
To sterilize the products (either in the form of bagged items such as pharmaceutical closures, or products with a sealed interior), a vacuum autoclave must normally be used because air trapped in the bag or interior must first be removed since it inhibits the process of steam sterilization. As described in U.S. Pat. No. 6,818,178, to achieve air removal, a vacuum steam autoclave typically subjects its contents to a conditioning or pre-vacuum phase in which the autoclave environment undergoes a series of alternating vacuum and steam cycles to remove air from the autoclave and the interior of the stopper bags. Three or four pulses are usually employed, each drawing a vacuum on the autoclave chamber and then introducing steam until the chamber reaches a predetermined positive pressure when the admission of steam is stopped and a vacuum is once again drawn. This type of pulsing is known to provide the greatest efficiency in quickly effecting the desired removal of air prior to sterilization.
Although sterilization barriers in the form of sheet materials are relatively inexpensive and thus attractive for many applications, they are difficult to use if they have to be formed to cover a non-planar opening or a projecting member. Correspondingly, it may be necessary to add an opening to a given product for the sole purpose of providing a sterilization barrier.
Having regard to the above-identified problems, it is an object of the present invention to provide a device comprising a sealed interior and an opening covered by a sterilization barrier, wherein the sterilization barrier allows the device to be manufactured in a cost-effective matter yet provides and high degree of design freedom for the device as such.